1. Field of the Invention
This invention relates to a peroxidase composition and to an antibody composition used in the field of diagnosis.
2. Description of the Related Art
Recently, in the field of clinical examination and diagnosis, measurement of various substances utilizing an immunological reaction and/or an enzyme reaction is widely performed.
Peroxidase is an enzyme which catalyzes the oxidation of various substances utilizing hydrogen peroxide as a hydrogen acceptor. Since peroxidase can be utilized for coloring reactions in which a color generator is oxidized by peroxidase to form a pigment, peroxidase is now more and more widely used as an enzyme marker for immunoassay and is used for the determination of hydrogen peroxide generated in an oxidation reaction of a target substance oxidized with the corresponding oxidase so as to quantify the target substance. However, peroxidase has poor stability, especially in the form of a liquid composition at a level of not more than several .mu.g/ml which is employed in practice, and it is very difficult to maintain activity when the liquid composition is stored at room temperature for a long time. Further, it is known that the activity of the peroxidase is largely reduced when the peroxidase composition is lyophilized.
On the other hand, various antibody compositions are now widely used in the field of immunoassay. It is also known that the activity of the antibody is reduced with time especially when the level of the antibody in the composition is low. This phenomenon occurs more severely when the storage temperature of the composition is higher.
Thus, it is difficult to store the peroxidase composition and antibody composition for a long time, and it is a serious problem for quality control of the composition used as a reagent for measurement or as a reagent for diagnosis. Therefore, the stabilization of the compositions is strongly demanded. In particular, as for the peroxidase-labelled antibody which is a conjugate of peroxidase and an antibody, in order to eliminate the possibility that a stabilization method for one component adversely affects the stability of another component, a stabilization method effective for the stabilization of both the peroxidase and the antibody is desired.